Skeltonhall Limited was founded in the UK in 1975 by Tony Hall, and in 1982 he developed and launched the 'Skeltonhall' Micro-set® MSD1 meter prover sphere detector.  Over the past 4 decades it has demonstrated itself to be the most dependable of instruments - with several thousand units in service globally, and near zero reported technical issues;

Micro-set® achieves the highest standards for reliability. 

In 2019, Tony's son, Justin Hall introduced the Micro-set® MSD2

The MSD2 upgrade includes the following key features:

  • 20x improved repeatability (vertical displacement resolution), now +/-0.01mm*                

  • Addition of IECEx hazardous area certification.

  • Addition of UKEX hazardous area certification.

  • Upgraded ATEX certification - now fully compliant with the current ATEX revision.

  • Increased upper ambient temperature limit (Tamb.), now +75 deg C.

All the above is achieved whilst maintaining the same core engineering team, working to the same designs and production procedures, utilising the same manufacturing & test equipment, all done in the UK right through from 1982 to the present day...  


Manufacture of the Micro-set® has transferred to Skeltonhall's sister company HALL Engineering.

*Micro-set® MSD2 has been tested by a UKAS Accredited independent testing laboratory using certified measuring equipment traceable to UK national standards.  Repeated testing (on detectors randomly selected from separate batches) shows all results fall within a peak to peak spread of 0.01mm - we have added 2x safety factor for additional confidence.

Micro-set® is:

  • Repeatable - high accuracy, far in excess of API Chapter 4 requirements.

  • Replaceable - fully interchangeable, and one model fits all from 3" to 36" and larger..

  • Robust - all stainless steel wetted parts with NACE MR 01-75 as standard.

  • Reliable - simplicity guarantees fault-free operation for year after year..

  • Reputable - Skeltonhall / HALL Engineering pedigree throughout..

A key feature of the MSD1 was the ability for any installed detector to be quickly replaced / upgraded as needed, and we have been keen to carry this feature forward to the MSD2.  Indeed, the MSD2 is completely compatible with the MSD1 pipe mounting boss & installation footprint/envelope.

This 100% interchangeability makes upgrading from MSD1 to MSD2 sphere detectors a quick and simple exercise.  Bringing the benefits of the higher accuracy (lower uncertainty), and more comprehensively certified device, immediately to your metering installation.

All pressure retaining materials are sourced from reputable & certified mills.  All manufacturing processes are carried out in the UK & each component is carefully tested at every stage.  Every unit is individually assembled by hand in the UK by skilled engineers with decades of experience.

Micro-set® is truly a 'Rolls-Royce' amongst sphere detectors...


Technical details:

 The 'Skeltonhall'  Micro-set® features a single mechanical moving part; the pressure balanced plunger/piston which has no dynamic seals.  The plunger is 100% bi-directional and is fully Nickel PTFE coated to prevent wear from abrasive particles, and ensure optimum long life.

The switch mechanism is a fully encapsulated SPST reed; ultimately simple and completely fail-safe.  It is totally isolated from the process (via an ANSI 600# / ANSI 1500# pressure rated stainless steel housing) and hermetically sealed from the environment.

For further detail please refer to the Technical Data Sheet (TDS) in our downloads section.


  • 600# / 1500# (or higher)

  • Ex d J.B. for site cable connection

  • Mounting boss for welding to prover pipe

  • Flushing port for debris laden or waxy products

  • 'Retro-fit' - adapted design or additional adapters supplied to fit other manufacturers' bosses

  • Boss alignment & pressure test tool



Technical Data Sheet

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IECEx Certificate

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ATEX Certificate

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UKEX Certificate

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IOM Manual

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ISO-9001 Certificate

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Contact us:

 HALL Engineering Services Ltd


 Tel:  +44 (0)791 746 7476

Product website:

Company website:


 HALL Engineering Services Ltd

 HALL House, Hayfield Close,

 Dronfield, Sheffield,

 S18 8RP, UK.


 HALL Engineering Services Ltd

 Lubeline Building, Unit 4,

 Collins Yard, Mill Lane, Dronfield,

 Sheffield, S18 2XL, UK.